Wheel balance tester



Oct. 13, 1942. R. n. sMlTH WHEEL BALANCE TESTER Filved Dec. 1, 1939 s sheets-sheet 1 lnbmtorj R09 D. Smith I t Gttomeg I R.' D. sMrrH WHEEL BALANCE TESTER` Find um. 11, 1939 s'sheis-:s'hee ...J 4 /V M o a a n m W GMG Zinnentor Roy D. Smath oct. 13, 1942. R, Q SMITH I v 2,298,656

WHEEL BALANCE TESTER Filed Dec. 1, 1939 3 Sheets-Sheet nnentor Rog D. mlih Gttonug Patented Cet. 13, 1942 UNITED STATESl PATENT OFFICE- WHEEL BALANCE TESTER Roy D. Smith, Davenport, Iowa, assignor to Bee Line Manufacturing Company, Scott County, Iowa, a corporation of Iowa Application December 1, 1939, Serial No. 307,043

Claims.

The present invention relates to the art of balancing, either statically or dynamically or both, articles which are substantially balanced about at least one axis. This invention has particular application to the balancing of vehicle wheels, including the tires, to the balancing of brake drums and to the balancing of combined wheels and brake drums. L. l

Among the objects of the presentl invention 'are the provision of an improved apparatus for determining the balance or unbalanceof a member intended to rotate about a xed axis; the provision of an improved apparatus for checking static balance of wheels; the provision of improved apparatus for checking dynamic balance of wheels; the provision of a machine for the purpose indicated which will be more` accuratethan any other machine now on the market; the provision of a machine for the use indicated which, in operation, will be independent of accurate leveling of the machine base; and such further objects, advantages, and capabilities as will` hereafter appear and as are inherent in the structure disclosed herein. My invention further resides in the combination, construction, and arrangement of parts illustrated in the accompanying drawings and, while I have shown therein a preferred embodiment of this invention, I desire the same to be understood as illustrative only and not as limiting my invention.

Dynamic off-balance of automobile wheels causes a vibration to be set up which is one of the main contributing causes of the commonly termed shimmy. It results Vin a tendency of the apparent geometrical axis to deviate from the axis of rotation. In use on an automobile, due to king-pin structure, this deviation will be damped out every 180. As is to be expected, in operation, the maximum deviation ordinarily either does not reach or else it exceeds the deviation which would be found if damping did not l take place. Regardless of this defect in giving a proper indication of the magnitude of olf-balance, it is customary practice in balance testing machines now on the market to incorporate a construction analogous to the king-pin of an automobile. Thus a false reading is obtained and adjustments made, which, though-corresponding to the test results, do not correct the defects in the Wheel tested.

It is accordingly a further object of this invention to provide a balance tester in which the' wheel is allowed freely to deviate in all directions and in which the deviation is not damped out.

In accordance with the present invention, a

Further, in accordance with balance tester is provided with which both accurate static and dynamic balancing maybe effected, such balancing being independent of leveling of the testing machine. More particularly a machine is provided having a self-aligning bearing, in combination with means -for mounting a wheel on said bearing whereby the wheel may tilt in any direction about said bearing, means for rotating a Wheel so mounted about a xed axis of rotation through said bearing independently of the dynamic balance of the wheel, said means for mounting a wheel subsequently supporting said wheel for rotation and tilting in any direction responsive to the dynamic balance of the wheel, and means for determining the deviation-of the apparent geometrical axis of the Wheel when rotating responsive to the dynamic balance from the fixed axis about which the wheel first rotates. this invention. a machine is provided with a self-aligning bearing, in combination with means for mounting a wheel on a portion of said bearing with the wheel generally horizontal and whereby the wheel may tilt bearing.

According to the method is provided supporting a wheel any direction, rotating the wheel about a fixed axis independently of the dynamic balance of the wheel, subsequently allowing the wheel to tilt about such axis responsive to the dynamic unbalance of the wheel, and determining the deviation, from said xed axis, of the position of the geometrical axis of said wheel. assumed during rotation, when in dynamic equilibrium.

Thus, among the primary advantages of this invention is the fact that dynamic oil-balance testing is performed on dynamic equilibrium conditions rather than dynamic ux conditions.

In the drawings annexed hereto and forming a part hereof,

Fig. 1 represents a substantially central vertical section through an apparatus embodying my invention and having a wheel mounted thereon to be tested, the wheel being shown in transverse section;

Fig. 2 represents a fragmentary portion of the present disclosure, a testing which comprises the steps of vstructure shown in Fig. 1, the wheel being shown in a position indicating out of balance;

Fig. 3 represents a portion of the structure for rotation and for tilting in` .treadle is depressed by the operator.

Fig.' 4 represents the same structure as Fig. 3 with the clamp disengaged;

Fig. 5 represents a plan view and Fig. 6 an elevation of an inclination measuring mechanism;

Fig. '7 is a perspective view of the apparatus without a wheel in place; and f Fig. 8 shows a measuring device applied to a wheel to determine the required length of a collar to be used for securing the proper positioning of the center plane of the Wheel.

Reference will now be made in greater detail to the annexed drawings for a more complete description of this invention. In the form of the device shown in Figs. 1 to '1 of the accompanying drawings, a body is provided comprising a wall member I, a top member 2 covering the upper end of the wall member I and which is bolted thereto as by bolts 3, and legs 4 --are provided, secured to the lower end of the wall member I. In the lower portion of the body member, a plate 5 issecured to the wall member I. A frame i rises from the plate 5 substantially centrally of the body of the machine and has secured to the upper end thereof a motor 1 with the shaft in substantially vertical position. A shaft 8 is slidably mounted in a vertical position in the top 2 and in a plate 9 adjustably secured to the plate 5. In the top 2, the bearing carrying the shaft 8 is a bushing I having an outwardly extending flange immediately above the top 2 and an upwardly extending flange thereabove on which is secured a self-aligning bearing. A pulley I2 secured to the bearing II is driven by the motor 1 through a pulley I4 secured to the motor shaft and a belt I5 drivingly engages the pulleys I2 and I4.

In order to move the shaft 8 vertically, a lever I8 is provided, pivotally mounted on the frame 6, having its inner end bifurcated to extend on opposite sides of the shaft 8, and having at its outer end a treadle I8' whereby an operator may' manually control the position of the lever and parts controlled thereby. A pair of collars I1, I8 is provided, with the collar I1 located above the lever I6 and collar I8 located below the lever. A spring I8 is located between the collar I1 and lthe lever to the left of the pivot, as seen in Fig. 1, to

take gradually the thrust of the lever when the An antifriction bearing 28 is interposed between the lever I6 and the spring I9 to allow free rotation of the shaft. In order to hold the treadle in elevated position, as shown in Fig, 1, a bolt 2I threadedly engages in an opening in the plate 5. being locked in adjusted position therein by means of a nut at its lower extremity. A spring 22 is interposed between the lever I 8 and the headof the bolt, normally elevating the treadle. If it is desired to place more pressure upon this end of the lever I6, the bolt is adjusted through the plate 5 and secured in adjusted position by means of this nut. If less pressure is desired, the adjustment is made in the opposite direction. For holding the treadle in depressed position with the shaft 8 raised, a shoulder is provided adjacent the lever I6 in the body member I under which the lever may be moved and from which it may be released by lateral movement.

A cylindrical flange 23 is provided upon the upper face of the pulley I2, the inner face of which' is conical, increasing in size downwardly. When the pulley I2 is in a position perpendicular to the shaft 8, the axis of the conical face is coincident with the axis of the shaft. A ring 24 is secured on the shaft 8 above the bearing II and within the' flange 23, the outer face of the ring being conical and complemental to the conical face of the flange 23. The ring 24 and the flange 23 are so proportioned asto allow vertical movement of the shalt 8, for engaging and disengaging the ring and flange. Accordingly, the flange and ring cooperate, the two being a conical clutch whereby, when the shaft 8 is raised by depressing the treadle I 6'-, the clutch is engaged, and whereby the shaft 8 is driven by the pulley I2. Further, it should be noted that, in case the pulley is out of position perpendicular to the shaft, engagement of the clutch will align the pulley into such position.

The shaft 8 extends above the ring 24 and is provided with a second self-aligning bearing secured to its upper end. A fixture 26 is provided having a cylindrical opening in the lower end thereof in which the outer ring of bearing 25 is secured by conventional means, such as, the ring and set screws shown. The cylindrical opening in the fixture is sufficiently large to allow substantial tilting of the xture with respect to the shaft 8. This fixture is provided with means for clamping a wheel thereto in position with the central portion of the wheel perpendicular to the axis of the fixture, with one of a pair of cooperating clamping means for holding the fixture in any particulartilted position with respect to the shaft, and with means for measuring the degree and direction of tilt of the fixture with respect to the shaft.

'l'he fixture 26 has formed integral therewith a downwardly and outwardly directed flange 21, which, being movable vertically with the shaft 8, is movable into and out of engagement with the pulley I2 exteriorly of the ange 23. Suicient clearance is provided between the inside of the conical flange A21 on fixture 26 andthe flange 23 on pulley I2 that the flange 21 and pulley I2 may operation hereinafter, and that it is immaterial in operation if foreign matter lodges on the lower end of the flange 21.

The 4fixture 2S is provided with a frustoconical ring 28 which is slidable onto the fixture, a collar l 28 being provided to space the ring from flange .21. Collars of various widths may be provided to allow adjustment of the position of the ring along the length of the fixture, whereby a wheel held thereby, regardless of the shape of any specinc wheel to be tested, may be properly secured to the fixture. The frustoconical ring 28 is of a size to extend only partially through the central openings of the automobile wheels in common usage. A bearing plate 30 is provided which is slidable upon the fixture. The lower face of the plate 3l should be substantially perpendicular to the axis of the fixture when the plate is in position thereon so as to hold the central portion of a wheel clamped between ring 28 and plate 38 perpendiculai to the axis of th'e fixture.

The upper end of the fixture is formed as a spindle which is threaded to provide for tightenrlng the plate 38 against the wheel by a nut 3l threadedly -engaging the spindle of the fixture and bearing against the plate.

A stud 32, which is cylindrical and coaxial with the axis of the nxture, is fixed to the upper end of the xture above the threaded portion. An inclinometer is pivotally mounted upon the stud, which inclinometer involves a bar 33 pivoted upon the stud to rotate upon the axis of the xture. To the upper surface of the bar 33, a level 34 is pivoted at one end thereof, a spring being provided to tilt the other end of the level toward the bar. A measuring screw 35 engages in an opening in the bar 33 below the free end of the level. This screw 35 is provided with a calibrated disc 36 cooperating with a pointer 31 carried by the bar 33. In the position of the screw 35 in which the zero calibration on disc 36 registers. with the pointer 31, the level is perpendicular to the axis of the fixture. When the screw is raised by turning, the level is tilted with respect to the axis of the fixture, the amount of tilt being inl the self-aligning bearing 25. For this purpose,

the structure shown in Fig. 8 is useful. This structure involves a bar 38 to be placed in engagement with the tire on the outer side of the wheel, and with the bar intersecting the axis of the wheel. A conical member 39 is positioned in the central opening, which member may be either the ring 28 from the balance testing machine or an auxiliary testing member. A rod is slidably mounted at the center of the bar 38 and is mounted for sliding movement transversely thereof. This rod 40 is calibrated to read directLv tire width and, in testing position, the rod is set at the calibration corresponding to the tire width. A ring 29 is selected which fits closely between rod 40 and the member 38. The bar 40 is of such a length that when this ring 29 is placed in the machine below cone 28, the tire gauged will have its center of gravity properly located.

Having then tested, as above described, for the size of collar 28 to be placed on the xture 26,

and with the proper collar in position and the Y' ring 28 adjacent thereto, the wheel is placed upon the ring with the inner sidev of the wheel up. This positioning is preferable in that it is then handy for placing balancing weights on the inner side of the wheel. It should, however, be under- `stood that the use of this method is not necessary to the use of this testing machine, since some other type of weights may be used, such as those which clamp to the rim of both sides of the wheel.

The plate 30 is next placed in position and secured by the nut 3| so that the central discof the wheel is perpendicular to the fixture. With the wheel then in position as described, and the treadle I8' Alowered, the motor 1 is started. Through Pulley Il and belt I5, the pulley I2 is driven. As the shaft 8 is elevated,'due to treadle I8 being lowered, the clutch to the shaft 8, which comprises flange 23 and ring 2l, is engaged and the cooperating clamp means comprising pulley l2 and ange 21 is disengaged. It will therefore be seen that the wheel is, in its position, not driven but is free'to rotate and to tilt onthe selfaligning bearing 28, in response to any static offbalance.- As the shaft 8 drives the internal port' tion of bearing 25, the support of the wheel in vthe bearing is substantially theequivalent of a support absolutely without friction, and far superior to the same bearing for support but without a driven support for the bearing. The heavy radial portion of the wheel will of course tilt the wheel, this portion being the lowest portion in the Y tilted position. A suitable weight may then be added to balance the wheel statically.

From the above description of static balancing operations it will be obvious that vertical positioning of the shaft 8 is unnecessary, theonly necessity being that it be nearly enough vertical to allow tilting of wheel in any direction.

With the wheel still supported on the ilxture, as heretofore stated, the dynamic balance testing is performed. First the treadle I6 is unlatched from the shoulder on the member I, as shown in Fig. 7. This ,allows the shaft 8 to move to lowered position whereby the conical clutch driving the shaft 8 is disengaged and the second clamp means, namely, the pulley I2 and ange 21, is engaged. This clamp means at this time acts as a clutch to transmit power from the pulley to the fixture and thereby rotate the wheel. Regardless of whether the clamp means clamps the fixture coaxial with the shaft 8, the wheel rotates on an axis through the self-aligning bearings II and 25. After the wheel has come up to speed, the treadle I6 is depressed to an inter- -mediate position in which both the conical clutch and the clamp means are disengaged. Free then to tilt responsive to gyroscopic tendencies of the wheel, the wheel and fixture will then tilt so that the dynamicaxis of rotation is in alignment with the axis of rotation, i. e., in alignment with the bearings Il and 25. If the wheel is dynamically off-balance, the apparent geometrical axis of the wheel will then be out of line with the axis of rotation and will be travelling in a cone. The

treadle I6 is then released to elevated positionv again engaging the clamping means and the power is shut olf. The Wheel may be stopped by means of a hand brake 4I pivotally carried at l by the top 2.

When the wheel is rotating freely, as described above, and the apparent geometrical axis is travelling in a cone, the same side of thewheel and vtherefore of the flange 211s always in the lower most position. Thus, the radial speed of rotation of the geometrical axis about the cone is equal to the radial speed of rotation ofthe wheel. When the flange 21 is lowered into engagement with the pulley l2, the pulley wiil tilt about its self-aligning bearing Il responsive to the tilt of the wheel and clamp the wheel in its tilted position with respect to the axis of rotation. The direction of tilt of the wheel indicates the direc-` tion of dynamic off-balance and the degree of tilt the amount of dynamic off-balance.

The inclinometer which may have been there-A tofore placed upon the stud 32 or may be placed there now .is used to indicate both the degree'and direction of dynamic onf-balance. After rotation of the article being tested has been stopped, if the central plane of the wheel is not perpendicular to axis 8, a test is made to determine the direction and amount of tilt. This is accomplished as follows: 'I'he inclinometer isor may be held stationary and the article being tested turned to determine the position at which the bubble in the level moves farthest to one end of its tube. Of course, the article may be held stationary and the level turned about its pivot 32, and the same result accomplished. Having now determined this position of greatest deviation, the disc 38 is turned until the level bubble is brought to certain position at the middle of the tube. The reading on the disc 36, at the point of pointer 31, is now noted. Next, the wheel is turned one hundred eighty degrees (180), the llevel being held stationary. Again the disc 36 is turned enough to level up the level and note is made of the number of divisions on the disc 3B which pass the pointer 31. The number of these necessary to bring the level back to a level condition is noted. 'I'his is a direct reading of the amount of weight required to be applied to the wheel to overcome its dynamic unbalance. The disc 36 may. be graduated in any units of weight desired, as, for example, ounces or grams. If the shaft 8 is known to be vertical, the second leveling of the level is unnecessary, as the reading on the disc 36 indicates the degree of off-balance, the calibration preferably..

being in ounces of weight at the edge ofthe'r'im. If it is not known that the shaft 8 is vertical, the wheel may be rotated 180 and the measurement repeated, as described above.

Inv this specification and in the subjoined claims, I denote by the term wheel not only the wheel proper or a Wheel and tire assembly, whether or not the hub and/or brake drum is attached thereto but also such other devices which are l intended to be balanced about an axis and rotated at high speed during use, such as airplane propellers.

Having novir described my invention, I claim:

l. A testing machine for determining off-balance of a wheel comprising a pair of self-aligning bearings, means to support said bearings, means carried by one of said bearings to support a Wheel with said one of said bearings located generally centrally of the wheel, means to rotate the wheel about the axial line of said bearings as the axis of rotation of the Wheel, the last mentioned means comprising in part a pulley surrounding the axial line of said bearings and supported by one thereof, said drive pulley being pivotally mounbed'with-reference to said axial line, and cooperating clamp means, one of which is carried by the wheel supporting means, and the other of which is supported by the other of said bearings, said clamp means being movable v into cooperating clamping engagement.

2. A testing machine for determining off-balanceof a Wheel comprising a. pair of self-aligning bearings, means to support said bearings, means carried by one of said bearings to support a wheel with said one of said bearings located generally centrally of the wheel, means to rotate the wheel about the axial line of said bearings as the axis of rotation of the wheel, cooperating clamp means, one of which is carried by the wheel supporting means, and the other of which is supported by the other of said bearings, said ,clamp means being movable into cooperating clamping engagement, and means for holding said clamping means disengaged and for then engaging said clamping means lwhen the wheel is rotating in dynamic equilibrium about the axis through said bearings.

3. A testing machine for determining dynamic off-balance, of a wheel comprising a support to which a Wheel may be attached, said support having a self-aligning bearing positioned, when the wheel is secured to the support, substantially on the .axis of the Wheel, cooperating clamp means, one of which is carried by said support, and a second self-aligning bearing, in general alignment with the rst mentioned bearing, and supporting the other of said cla'mp means,said clamp means being relatively movable together into cooperating engagement, each of the two clamp means being tiltable relatively to .he common axis of the self-aligning bearings.

4. A machine for testing the balance of a wheel comprising a shaft, a pair of self-aligning bearings, in one of which the shaft is slidable and the other of which is fixed to the shaft, a xture carried by one of said bearings to which a wheel may be centrally secured, said fixture being tiltable with reference to said shaft so that the axes of the twolmake a Vsmall angle with relation to each other, cooperating clamp means, one of which is supported by the bearing other than that supporting the fixture, and the other of said clamping means remaining fixed with respect to said xture in any tilted position of the xture with respect to said shaft, when the two clamping means yare in clamping engagement, and means for determining the amount to which said fixture is tilted with respect to said shaft.

5. In a machine for determining wheel unbalance, a generally vertically 'extending shaft, means for supporting said shaft in a generally vertical position, a self-aligning bearing on said shaft to support a wheel for rotation about said shaft, means to connect a Wheel to said bearing,

means to rotate said last named means to cause vertical position, a sel-.aligning bearing on said shaft to support awheel'for rotation about said shaft, means to connect a wheel to said bearing, means to rotate said last named means to cause rotation of a wheel mounted thereon, and means for holding the wheel in any inclined position as-umed by it during rotation.

7. In a wheel balance tester, a shaft having adjacent an end thereof a self-aligning bearing, a lwheel-supporting structure surrounding said bearing and connecting a vehicle wheel thereto, means to lift the bearing and thereby the wheel so that the'wheel may assume a tilted position of stable equilibrium during rotation, and means to hold said. wheel in such tilted position.

8. In a wheel balance tester, a shaft having adjacent an end thereof a self-aligning bearing, a. wheel-supporting structure surrounding said bearing and connecting a vehicle wheel thereto, means to lift the bearing and thereby the wheel so that the wheel may assume a tilted positionof stable equilibrium during rotation, means to hold said wheel in such tilted position, and means for imparting rapid rotation to the wheelsup porting structure.

9. Ina wheel balance tester, a shaft having adjacent an end thereof a self-aligning bearing, a wheel-.supporting structure surrounding said bearing and connecting a vehicle Wheel thereto,

with the geometrical axis of the wheel passing approximately through the center of oscillation of the rst mentioned self-aligning bearing whereby the wheel is free to assume an inclined position during rotation, the pulley being capable -of oscillating into positions other than at a right angle to the axle and of having its geometrical axis parallel' tcrfthat of the wheel, said clutch parts, when brought together, holding the wheel lo against change of its condition of inclination.

ROY D. SMITH. 

